I. Field of the Invention
This invention relates generally to apparatus for performing angioplasty procedures for opening partially occluded blood vessels, and more particularly to a hand-operated inflation and fluid dispensing device adapted to be connected to the proximal end of an angioplasty catheter for either inflating the expander member on that catheter or supplying a radiopaque contrast medium through the catheter and out its distal end.
II. Discussion of the Prior Art
There is described in the Schjeldahl et al U.S. Pat. No. 4,413,989 the configuration of an angioplasty catheter specifically adapted to treat stenotic lesions located in one of the coronary arteries. Basically, the catheter comprises an elongated tubular member having a nondistensible expander member disposed proximate its distal end, the expander member being inflatable by introducing a fluid through the proximal end of the catheter whereby it flows through the lumen of the catheter and out one or more ports in the side wall of the tubular member which are surrounded by the expander member.
In treating stenotic lesions, it is often necessary to pressurize the expander member to a pressure in the range of from 7 to 10 atmosphere or more. This pressure must be sustained for periods of up to 30 seconds or more.
There is currently on the market an angioplasty catheter inflation device in the form of a molded plastic housing configured to contain a hypodermic-type syringe having a diameter of about 6.5 cms. and whose output port is coupled to the proximal end of the tubular catheter body. The plunger of the syringe is suitably positioned relative to integrally molded finger grips on the housing so that the plunger will fit in the palm of the hand as the user's fingers wrap about the finger grips. By squeezing, fluid is ejected from the syringe and through the elongated catheter so as to inflate the expander member. The device is constructed in accordance with the Lundquist U.S. Pat. No. 4,439,185 assigned to Advanced Cardiovascular Systems, Inc. of Mountain View, Calif. Using this prior art device, however, it is extremely difficult for the cardiologist or technician to sustain the necessary pressures for the time interval during which the expander is pressurized. It requires a very strong grip and often it is difficult to hold the device steady and at the desired inflation pressure due to the strong force which must be applied to the inflation device. While the applied force can be reduced by reducing the overall diameter of the syringe's piston, this necessarily reduces the volume of fluid available to, for example, initially fill the lumen of the catheter and the expander with fluid or to later inject contrast media when the site being treated is to be inspected using fluoroscopic techniques.
Described in the Kokernak U.S. Pat. No. 4,583,974 is an inflation syringe for a balloon catheter which has a cylindrical body in which a tubular glass cylinder is enclosed. A movable plunger is disposed within the glass cylinder and is attached to a threaded shaft extending outwardly from one end of the syringe. A threaded latch member is pivotally secured to the body for selectively engaging the threads on the movable plunger. When the latch member is engaged with the threaded shaft, rotation of the shaft results in a controlled incremental axial movement of the plunger and a corresponding increase or decrease in the hydraulic pressure within the catheter system. When the latch is disengaged, however, the shaft is free to move axially, allowing quick deflation of the angioplasty balloon.